Audio and video data synchronization apparatus for recording and reproducing system

Abstract

A frequency converting circuit serves to generate a clock signal of a video sampling frequency from one of a clock signal or a sync signal outputted from a digital audio interface. An oscillator serves to generate a clock signal of the video sampling frequency. A video reference generating circuit serves to generate a video timing signal, an audio timing signal, and black burst data from one of the clock signals generated by the frequency converting circuit and the oscillator, and from an output reference video signal. In cases where the recording audio data is recorded or edited, a first switching device replaces the recording video data by the black burst data, and feeds the black burst data to the video recording processing circuit. In these cases, a second switching device replaces the video-sampling-frequency clock signal from the oscillator by the video-sampling-frequency clock signal from the frequency converting circuit, and feeds the video-sampling-frequency clock signal from the frequency converting circuit to the video reference generating circuit. In addition, a third switching device suspends detection of an output reference fed to the video reference generating circuit, and inhibits a timing reset of the video reference generating circuit.

What is claimed is: 
     
       1. In a system wherein a video recording processing circuit and an audio recording processing circuit process digital recording video data and digital recording audio data; output data from the video recording processing circuit and the audio recording processing circuit is recorded into a recording medium by using a sync signal of the digital recording video data as a reference; a video reproducing processing circuit and an audio reproducing processing circuit process data reproduced from the recording medium; and reproduced video data and reproduced audio data are outputted in synchronism with an externally generated reference video signal inputted to the system, video and audio data recording a reproducing apparatus usable in combination with a digital audio interface, comprising: a frequency converting circuit for generating a clock signal of a video sampling frequency from one of a clock signal or a sync signal outputted from the digital audio interface;   an oscillator for generating a clock signal of the video sampling frequency;   a video reference generating circuit for generating a video timing signal, an audio timing signal, and black burst data from one of the clock signals generated by the frequency converting circuit and the oscillator and from the external reference video signal;   said video reference generating circuit including reference-detecting means for detecting the external reference video signal;   first switching means for, in cases where the recording audio data is recorded or edited, replacing the recording video data by the black burst data and feeding the black burst data to the video recording processing circuit;   second switching means for, in cases where the recording audio data is recorded or edited, replacing the video-sampling-frequency clock signal from the oscillator by the video-sampling-frequency clock signal from the frequency converting circuit and feeding the video-sampling-frequency clock signal from the frequency converting circuit to the video reference generating circuit; and   third switching means for, in cases where the recording audio data is recorded or edited, suspending detection of the external reference video signal by said reference detecting means in the video signal by said reference detecting means in the video reference generating circuit, and inhibiting a timing reset of the video reference generating circuit.   
     
     
       2. The video and audio data recording and reproducing apparatus of claim 1 wherein the oscillator comprises means for generating the video-sampling-frequency clock signal from burst components of the external reference video signal, the video sampling frequency being equal to four times a color subcarrier frequency, wherein the frequency converting circuit comprises a frequency converter for executing a frequency conversion process on the clock signal or the sync signal outputted from the digital audio interface, and converting the clock signal or the sync signal into a horizontal-frequency signal, a PLL circuit including a phase comparator for comparing a phase of the horizontal-frequency signal outputted from the frequency converter and a phase of a horizontal-frequency signal outputted from the video reference generating circuit, said PLL circuit outputting a clock signal having a frequency which is controlled in response to a result of the comparison between the phase of the horizontal-frequency signal outputted from the frequency converter and the phase of the horizontal-frequency signal outputted from the video reference generating circuit, and wherein the video reference generating circuit comprises means for frequency-dividing the video-sampling-frequency signal and converting the video-sampling-frequency signal into the horizontal-frequency signal, means for feeding the horizontal-frequency signal to the frequency converting circuit. 
     
     
       3. The video and audio data recording and reproducing apparatus of claim 1 wherein the oscillator comprises means for generating the video-sampling-frequency clock signal from burst components of the external reference video signal, the video sampling frequency being equal to four times a color subcarrier frequency in a PAL television system, wherein the frequency converting circuit comprises a frequency converter for executing a frequency conversion process on the clock signal or the sync signal outputted from the digital audio interface, and converting the clock signal or the sync signal into a horizontal-frequency signal having a frequency corresponding to a predetermined horizontal-frequency of a video signal, a first PLL circuit including a phase comparator for comparing a phase of the horizontal-frequency signal outputted from the frequency converter and a phase of a horizontal-frequency signal outputted from the video reference generating circuit, said first PLL circuit outputting a clock signal having a frequency which is controlled in response to a result of a comparison between the phase of the horizontal-frequency signal outputted from the frequency converter and the phase of the horizontal-frequency signal outputted from the video reference generating circuit, and wherein the video reference generating circuit comprises a first horizontal counter for frequency-dividing the video-sampling-frequency signal and generating a first horizontal-frequency pulse signal having a phase approximately equal to a phase of a horizontal sync signal, a second PLL circuit for generating a clock signal of a frequency equal to an integer multiple of the horizontal-frequency on the basis of the first horizontal-frequency pulse signal, and a second horizontal counter for generating a second horizontal-frequency pulse signal from the clock signal generated by the second PLL circuit, and feeding the second horizontal-frequency pulse signal to the frequency converting circuit. 
     
     
       4. The video and audio data recording and reproducing apparatus to claim 1 wherein the oscillator comprises means for generating the video-sampling-frequency clock signal from burst components of the external reference video signal, the video-sampling-frequency being equal to four times a color subcarrier frequency, wherein the frequency converting circuit comprises a frequency converter for executing a frequency conversion process on the clock signal or the sync signal outputted from the digital audio interface, and converting the clock signal or the sync signal into a horizontal-frequency signal, a PLL circuit including a phase comparator for comparing a phase of the horizontal-frequency signal outputted from the frequency converter and a phase of a horizontal-frequency signal outputted from the video reference generating circuit, said PLL circuit outputting a clock signal having a frequency which is controlled in response to a result of a comparison between the phase of the horizontal-frequency signal outputted from the frequency converter and the phase of the horizontal-frequency signal outputted from the video reference generating circuit, and wherein the video reference generating circuit comprises a counter for frequency-dividing the video-sampling-frequency signal and counting a color subcarrier phase and horizontal and vertical phases, a ROM receiving an output signal from the counter as an address signal and outputting digital data of a black burst signal, a digital-to-analog converter for converting the digital data of the black burst signal into a corresponding analog black burst signal, a low pass filter for removing high-frequency components from the analog black burst signal, and a horizontal sync separating circuit for generating the horizontal-frequency signal fed to the frequency converting circuit on the basis of an output signal from the low pass filter. 
     
     
       5. A video and audio data recording apparatus comprising a video recording processing circuit for processing first video recording data into second video recording data, and generating a timing control signal on the basis of the first video recording data; a digital audio interface; an audio recording processing circuit for processing first audio recording data into second audio recording data; means for recording the second video recording data and the second audio recording data into a recording medium; and servo-control means for controlling the recording means in response to the timing signal; the improvement comprising: means for feeding output data from the digital audio interface to the audio recording processing circuit as the first audio recording data;   means for determining a fixed-frequency timing component of the output data from the digital audio interface;   means for generating a reference clock signal on the basis of the fixed-frequency timing component of the output data from the digital audio interface, the reference clock signal having a fixed frequency relation with the fixed-frequency timing component of the output data from the digital audio interface;   means for generating reference data on the basis of the reference clock signal, the reference data corresponding to a black burst signal; and   means for feeding the reference data to the video recording processing circuit as the first video recording data.   
     
     
       6. The video and audio recording apparatus of claim 5 wherein the reference clock signal has a frequency equal to a predetermined frequency of a sampling clock signal related to the first video recording data. 
     
     
       7. A video and audio data recording apparatus usable in combination with digital audio interface, comprising: means for recording video data and audio data into a recording medium;   means for generating a first timing signal on the basis of the video data;   means for extracting audio data from an output signal of the digital audio interface, and feeding the extracted audio data to the recording means;   means for detecting presence and absence of the video data;   means for generating a second timing signal on the basis of the output signal of the digital audio interface in the absence of the video data; and   servo-control means for controlling the recording means in response to the first timing signal in the presence of the video data and in response to the second timing signal in the absence of the video data.   
     
     
       8. The video and audio data recording apparatus of claim 7 wherein the second-timing-signal generating means comprises means for generating the second timing signal on the basis of a fixed-frequency component of the output signal of the digital audio interface, the second timing signal having a fixed frequency relation with the fixed-frequency component of the output signal of the digital audio interface.